Tool-steel alloy.



rnvrnn eras aria oria RAJDCLYFFE FURNESS JENKINTOWN, ANDBICHARD H. PATCH, 0F PHILADELPHIA,

PENNSYLVANIA, ASSIGNORS TO THE MIDVALE STEEL COMPANY, OF PHILADEL- PHIA, PENNSYLVANIA, A CORPORATION OF ?ENNSYLVANIA.

TOOL-STEEL ALLOY.

No Drawing.-

To all whom it may concern Be it known that we, RADOLYFFE FURNEss and RICHARD H. PATCH, citizens of the United States, residing at, respectively,-

Jenkintown, county of Montgomery, State of Pennsylvania, and Philadelphia, county of Philadelphia, State of Pennsylvania, have invented a new and useful Improvement in Tool-Steel Alloys, of which the following is a full, clear, and exact description.

llhe object of our invention is to produce a new and improved high speed tool steel having a substantially higher efficiency than known tool steels to which it is most-analogous. v

A high speed tool steel containing about 5% of chromium, about 18% of tungsten, about 1% of vanadium, and about &% of cobalt, is known. 'A high speed tool steel of the following composition is also known: chromium from 2.5 to 4%, tungsten from 16.5 to 20%, vanadium from 1 to 2%, and cobalt from 3 to 7%. Other tool steels containing the same ingredients with slightly different proportions are also known. These tool steels are very eflicient, but they are so expensive that other less expensive tool steels of less efliciency are very frequently of the tool steels hereinbefore mentioned.

Above 15% the increased efficiency imparted by the cobalt increases at a pronouncedly reduced ratio, so that the increasedefliciency of steel containing cobalt beyond 18 or 20% does not compensate for the increased cost.

While we have spoken of displacing the tungsten by cobalt, we do notmean to be understood as asserting that the tungsten must be reduced to the exact extent that the cobalt is increased, it being impracticable to reduce the tungsten to. below about 9%..-

Specification of Letters Patent.

Patented Dec. '5, 1916..

Application filed January 19, 1916. Serial No. 72,901.

Inasmuch as under present conditions the price of tungsten is nearly six times that of cobalt, it will be understood that our improved tool steel is much less expensive, even though the cobalt be increased'out of proportion to the decrease of tungsten; and that even under normal conditions, during which the price of cobalt somewhat exceeds that of tungsten, the greatly increased eficiency of our improved tool steel makes it actually more economical.

We contemplate employing varying percentages of the several ingredients of our improved composition within the following ranges: chromium 2 to 6%; tungsten 9 to 15%; cobalt 5 to 20%; and vanadium 1 to 2%. The vanadium may be dispensed with, inasmuch as its addition does not change the essential characteristics of the tool steel, although its incorporation in the composition somewhat improves it. The carbon content of the tool steel may vary from 55% to 15%.

A preferred composition is as follows chromium 4%; tungsten13.5%; vanadium 1.5%; cobalt 15%; iron 65%; carbon .65%;

with traces of other ingredients usuallypresent in steel.

While it has been heretofore suggested that the percentage of cobalt in tool steels of the character of those herein referredto.

may range as high as 15 per. cent; no mformation is given, 1n connectlon w1th such statement, with respect to the proportions.

of chromium and tungsten to be used there with, and still less has there been any'suggestion of the .discovery, underlying our present invention, that cobalt may profitably displace tungsten, or of the extent to. which such displacement is practicable, or of the fact that by such substitution, within the limits specified herein, the vefidiminution in cost.

While we have mentioned that the steel 100 above described is adapted especially for high speed tool steel, it 'is also capable of other uses, as for example any device for working hot metal, such as gripper dies, nut piercers and header dies. For such purposes the steel should contain from .20 to ,60 per cent. of carbon.

ciency of the tool steel will not only be increased, but multiplied, and with an actual-F"- Having now JI'ullj described our .inven- In testimony of which invention, wehave 10 tion, what we claim and desire to protect hereunto set our hands at Philadelphia, by Letters Patent is 1 Penna, on this 15th day of January, 1916.

1. A high speed too steel containing 5 chromium 2 tor6%, tungsten 9 to 15%, and

c0balt 5 to 20%. Y

2. A high speed tool steel containing from Witnesses: 2 to 6% chromium, less than 15% of -HAR1 ;Y D. SIEGFRIED, tungsten, and not less than 10% of cobalt. Jos. ENTWISLE. 

